Aeroplane propeller



Nov. 10, 1931. w. F. TRIPLETT 1,831,692

AEROPLANE PROPELLER Filed March 19. 1930 2 Sheets-Sheet l ATTORNEY Nov. 10, 1931. w gg-r-r 1,831,692

AEROPLANE PROPELLER Filed March 19. 1930 2 Sheets-Sheet 2 W1 29%)? Ze fzfmmm ATTOR NEY Patented Nov. 10, 1931 UNITED STATES WILLIAM TRIPLETT, F GRAND JUNCTION,.COLORADO YAEROPLANE rnornnnnn Application fil ed March 19,1930. Serial No. 437,216.

This invention relates to aeroplane propellers and has as its'primary object to provide a propeller which will furnish a uniform flow of air at all speedsin a take-off of the aeroplane and in straight flight, and which will likewise reduce or substantially eliminate the usual drumming-or droning noises attending the operation of an ordinary propeller.

Another object of the invention is to pro- .vide a propeller which will reduce the liability of stalling in flight inasmuch as it creates in flight, as stated, uniform flow of air at any speed of the engine. 7 1 J This invention also consists in certain other featuresof construction and in the combination and arrangement of the several parts, to be hereinafter fully described, illustrated in the accompanying drawings and specifically pointed out in the appended claims, it being understood that minor changes may be made so long as they fall within the scope of the claims. Indescribing my invention in detail, reference will be had to the accompanyingdraw:

ings wherein like characters denote like or corresponding parts throughout the several views, and in which V V Figure 1 is a view inside elevation of a propeller embodying the invention.

Figure 2 is a front elevationthereof. t Figure 3 is a detail vertical transverse sectional View taken substantially on the line 3-3 of Figurel looking in the direction indicated by the arrows. f

Figure 4 is a transverse sectional view taken substantially on the line 1-4 of Figure 3 lookingin the direction indicated by the arrows. I

Figure 5- is a transversesectional view through one of the blade units taken on the line 5-5 of Figure llooking in thedirection indicated by the arrows. I i p In the drawings the numeral 1 indicates the propeller shaft and the'numeral 2 indicates a headwhich is of metal and which is mounted upon the propeller shaft and held for rotation therewith by a key 3. The head is formed in diametrically opposite sides with recesses 4 in its intermediate portion and between cylindrical portions 5 and the said recesses serving purposes which will presently be explained- Each propeller blade comprises a main blade 6 which is of any suitable material and which is formed with a lon- 65 gitudinally extending opening indicated by the numeral 7 and the said openings of the two blades extend from a point near the outer ends of .the blades to the head 2. The blades 6, at their innerends and at opposite sides of the inner end of each opening 7 are provided each with offset portions '8 which are disposed against one side'of a respective one of two pairs of lugs 9 formed integrally with the head at diametrically opposite sides of its portions 5, and plates 10 are disposed against the other sidesof the lugs 9 and rivets or other securing elements 11 are secured through the oflsetportions 8, the plates 10and the lugs 9, and inthis mannerthe blades 6 are connectedat their inner ends for rotation with the shaft 1, it being observed that each plate 10 islikewise securedby a rivet or other suitable fastening element 12 to the respective inner end portion of the respective blade 6.

In addition to the blades 6 which are di reotly rotated by. thejshaft 1 and which shaft is in turn rotated by the motor of the aeroplane, each blade unit comprises an auxiliary blade which is indicated in general bythe numeral 13 and these auxiliary blades are of a length equal approximately to the length of the openings 7 and of a width nearly equal to the width of said openings so that the blades 13 maybe received within the openings vfor rotary motion in a manner to be presently explained. Each blade 13 preferably has its longitudinal edge portions curved in opposite directiona-s indicated at 14.

Mounted in each bearing ball race 15 which is of annular form and the numeral 16 indicates a cap plate which is disposed against the side of the head 2 in which the respective recess 4 is formed, so that the bearing race 15 will be held Within the recess,

the plate 16 being formed with a symmetricaljly located opening 17. The numeral 18 indicates shanks which extend from heads 19 109 -tions per minute.

stud 20 being headed or overturned as indi-- cated by the numeral 23 so asto be connected with the head 19 of the shank 18. The hearing race 15 and bearing race 22 are suitably grooved in their mutually opposing sides as is also the inner peripheral portion of the head 19 and bearing balls 24 are arranged within the annular race thus formed as a unit.

Each shank is formed with two fiat sides indicated; by the numeral24and these flat sides are arranged planes converging in. the direction of the outer end of the shank 18. Each blade 13-is'tapered at its inner end and this tapered inner end isslightly deflected as at 25 to provide aportion 26 which is disposed against one of the sides 24. A plate 2Tis disposed against the other side 24 of each shank l8 and. rivets 28 are secured through the portion26 of each. blade, through the tapered portion of the respective shank and through the respective plate 27 and in this manner the inner endsotthe blades 13 are connected with the shank so that they will rotate with the head 19.

It will be observed by reference to Figures 1 and 5 of the drawing that-in one position of theblades 13, the blades are substantially located within theopenings'Z in the respective blades 6 but due to the curvilinear contour of their longitudinal edge portions 14;, they will, when the propeller, as-ua Whole, is retated, be caused to rotate rapidly- It be evident that the blades 13. will be rotated at a greater speed, about an axis .at right angles to the axis of the rotation of the shaft 1 than the speed at which the blades 6 are rotated in the atmosphere and that the blades 13' will not only be rotatable with re spect to the blades 6 but also rotatable with the said blades 6. Due to this construction and arrangement of parts the rotation of the propeller blades will create a uniform flow of air at all speeds, not only in the take-oil of the aeroplane, but also in straightflight and due to the fact that the blades rotate axially of the blades 6', the noises usually created by blades of the same type as the blades 6 but imperforate, will not be produced.

In actual tests on 21 horsepower'motor at 17,050 revolutions per minute and using a propeller constructed from alloy steel a'nd measuring two feet long and five inches wide, it has been found the air will be smoothed out'at various speeds of the motor from .800 revolutions per minute up to 17,050 revolu These tests were made from diiferent angles from the natural flow of wind current- This condition is created by the small blades being free to revolve by Velocity and at an increased speed from the main blade which is connected to the drive shaft of the motor, which revolution speed will govern the main blade speed. lVitha straight propeller blade constructed to pull or worm. its way through the air as it cleavesthe air at a speed that varies from 250 to 300 revolutions per minute from climbing to cruising speed it disturbs the natural flow of air current. The highly dis turbed air currentin rushing and returning to its normal state from the pulling edges of the'propeller under the present constructions creates the drone or sharp drum noises. The propeller blade hereinbefore' described, by the small blade revolving independently and at-an increasedrate ofspeed, will create a small flow of air current inside of the main currentascreated by the main blade in cleaving the current oi flow ofthis highly disturbed air, tlrus fanning and reta-rdingthe air as it attemptsto; return to its original natural flow, thus dulling the sharp .drone and drum; In other words, to convey the idea, the construction hereinbeiiore described will act as a silencer as. the highly disturbed air can not rush back in its natural state at a high rate of compact. Under actual tests in'the placing of Sll'lilill holes tolead or move ahead of the main blade edges it will increase the .efiiciency and fiurther reduce the noises heretofore mentioned andnot retard the efficiency of the-mainblade.

What I claim is :j 1.. An aeroplane propeller comprising a hub, blades radiating therefrom and each comprising a fixed'main .blade rotatable with the hub and provided with a longitudinal openingtherein, and an auxiliary blade mounted in the opening-of each main blade and rotatable therein about an axis radial to the axis of rotation of the hub, each auxiliary blade having its longitudinal marginal portions deflected in opposite directions whereby to ofi'er resistance to air currents and whereby the said auxiliary blade will be rotated with respect to the main blade by the-air currents passing through said open- 2. An aeroplane propeller comprising a.

hub, blades radiating therefrom and each comprising a fixed main blade rota-table with the hub and provided with a longitudinal opening therein, and an auxiliary blade mounted in the opening of eachmain blade and rotatable therein about an axis. radial to the axisof rotationofthe huh,each auxiliary blade having its longitudinal marginal portions curved in voppositedirections whereby "to oiler resistance to air currents and whereby the said auxiliary blade will be rotated with respect to the main blade by the air currents passing through said opening.

3. An aeroplane propeller comprising a hub, blades radiating therefrom and each comprising a fixed main blade rotatable with the hub and provided with a longitudinal opening therein, and an auxiliary blade mounted in the opening of each main blade and rotatable therein about an axis radial to the axis of rotation of the hub, each auxiliary blade having its longitudinal marginal portions curved in opposite directions whereby to offer resistance to air currents and whereby the said auxiliary blade will be rotated with respect to the main blade by the air currents passing through said opening, the said marginal portions of each auxiliary blade projecting beyond opposite sides of the main blade.

4. An aeroplane propeller comprising a hub, blades radiating therefrom and each comprising a fixed main blade rotatable with the hub and provided with a longitudinal opening therein, an auxiliar blade associating with each of the main lades and including a shank having a rotatable bearing in the respective side of the said hub, whereby to provide for free rotation of the auxiliary blade with respect to the main blade and about an axis radial to the axis of the hub, each auxiliary blade having a portion offerin resistance to air currents, whereby the said auxiliary blade will be rotated with respect to the main blade by the air currents passing through said opening.

In testimony whereof I afiix my signature.

' WVILLIAM F. TRIPLETT. 

